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3 years ago

Describe Dalton’s atomic theory.

Chemistry

1 answer:

ser-zykov [4K]3 years ago

6 0

Answer:

Dalton's atomic theory was the first complete attempt to describe all matter in terms of atoms and their properties.

Dalton based his theory on the law of conservation of mass and the law of constant composition.

The first part of his theory states that all matter is made of atoms, which are indivisible.

The second part of the theory says all atoms of a given element are identical in mass and properties.

The third part says compounds are combinations of two or more different types of atoms.

The fourth part of the theory states that a chemical reaction is a rearrangement of atoms.

Parts of the theory had to be modified based on the existence of subatomic particles and isotopes

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... in neutralization reactions, for example:

NaOH + HCl = NaCl + H₂O

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3 years ago

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State two reasons atom X is different than atom X+1

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Explanation:

atom X

it is neutral

and may not exist independently

atom X+1

it is ion which has a charge on it positive or negative

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3 years ago

How many moles of MgO are produced when .250 mol of Mg reacts completely with O2

nignag [31]

Answer:

0.250 moles of MgO are produced when 0.250 mol of Mg reacts completely with O₂

Explanation:

In first place, the balanced reaction between Mg and O₂ is:

2 Mg + O₂ ⇒ 2 MgO

By stoichiometry of the reaction (that is, the relationship between the amount of reagents and products in a chemical reaction), the following amounts of reactants and products participate in the reaction:

Mg: 2 moles
O₂: 1 mole
MgO: 2 moles

Then you can apply the following rule of three: if by reaction stoichiometry 2 moles of Mg produce 2 moles of MgO, 0.250 moles of Mg, how many moles of MgO will they form?

$moles of MgO=\frac{0.250 moles of Mg*2 moles of MgO}{2 moles of Mg}$

moles of MgO= 0.250

<u><em>0.250 moles of MgO are produced when 0.250 mol of Mg reacts completely with O₂</em></u>

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3 years ago

What is the molarity of a solution prepared by dissolving 10.7 g NaI in 0.250 L?0.0714

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Answer:0.286M

Explanation:

10.7g / 149.89g/mol×0.25L

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3 years ago

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When a 17.7 mL sample of a 0.368 M aqueous hypochlorous acid solution is titrated with a 0.301 M aqueous barium hydroxide soluti

nordsb [41]

Answer:

pH = 12.98

Explanation:

Step 1: Data given

Volume of aqueous hypochlorous acid solution = 17.7 mL = 0.0177 L

Molarity of aqueous hypochlorous acid solution = 0.368 M

Molarity of aqueous barium hydroxide solution = 0.301 M

Volume of aqueous barium hydroxide solution = 16.2 mL = 0.0162 L

Step 2: The balanced equation

2HCl + Ba(OH)2 → BaCl2 + 2H2O

Step 3: Calculate moles

Moles = molarity * volume

Moles HCl = 0368 M * 0.0177 L

Moles HCl = 0.0065136 moles

Moles Ba(OH)2 = 0.301 M * 0.0162 L

Moles Ba(OH)2 = 0.0048762 moles

Step 4: Calculate the limiting reactant

For 2 moles HCl we need 1 mol Ba(OH)2 to produce 1 mol BaCl2 and 2 moles H2O

HCl is the limiting reactant. It will completely be consumed 0.0065136 moles. Ba(OH)2 is in excess. There will react 0.0065136/2 = 0.0032568‬ moles. There will remain 0.0048762 moles - 0.0032568‬ = 0.0016194 moles

Step 5: Calculate molarity Ba(OH)2

Molarity Ba(OH)2 = moles / volume

Molarity Ba(OH)2 = 0.0016194 moles / 0.0339 L

Molarity Ba(OH)2 = 0.04777 M

Step 6: Calculate [OH-]

Ba(OH)2 → Ba^2+ + 2OH-

For Ba(OH)2 we have 2* [OH-]

[OH-] = 2*0.04777 = 0.09554 M

Step 7: Calculate pOH

pOH = -log[OH-]

pOH = -log(0.09554)

pOH = 1.02

Step 8: Calculate pH

pH = 14 - 1.02

pH = 12.98

8 0

3 years ago